Address comments from code review

src/constants.ts

@@ -107,3 +107,8 @@ export const FAKE_TITLE_LOGO_CHANCE = 10000;
  * Using rare candies will never increase friendship beyond this value.
  */
 export const RARE_CANDY_FRIENDSHIP_CAP = 200;
+
+/**
+ * The maximum number of times a player can Terastallize in a single arena run
+ */
+export const MAX_TERAS_PER_ARENA = 1;

src/data/moves/move.ts

@@ -94,7 +94,7 @@ import i18next from "i18next";
 import { applyChallenges } from "#utils/challenge-utils";
 import { MovePhaseTimingModifier } from "#enums/move-phase-timing-modifier";
 import type { AbstractConstructor } from "#types/type-helpers";
-import { canTerastallize, willTerastallize } from "#utils/pokemon-utils";
+import { canSpeciesTera, willTerastallize } from "#utils/pokemon-utils";
 
 /**
  * A function used to conditionally determine execution of a given {@linkcode MoveAttr}.
@@ -5320,7 +5320,7 @@ export class TeraBlastTypeAttr extends VariableMoveTypeAttr {
     const coreType = move.type;
     const teraType = user.getTeraType();
     /** Whether the user is allowed to tera. In the case of an enemy Pokémon, whether it *will* tera. */
-    const hasTeraAccess = user.isPlayer() ? canTerastallize(user) : willTerastallize(user);
+    const hasTeraAccess = user.isPlayer() ? canSpeciesTera(user) : willTerastallize(user);
     if (
       // tera type matches the move's type; no change
       !hasTeraAccess

src/ui/handlers/command-ui-handler.ts

@@ -1,3 +1,4 @@
+import { MAX_TERAS_PER_ARENA } from "#app/constants";
 import { globalScene } from "#app/global-scene";
 import { getPokemonNameWithAffix } from "#app/messages";
 import { getTypeRgb } from "#data/type";
@@ -198,9 +199,12 @@ export class CommandUiHandler extends UiHandler {
 
   canTera(): boolean {
     const activePokemon = globalScene.getField()[this.fieldIndex];
+    const currentTeras = globalScene.arena.playerTerasUsed;
     const canTera = activePokemon.isPlayer() && canTerastallize(activePokemon);
-    const plannedTera = globalScene.currentBattle.preTurnCommands[0]?.command === Command.TERA && this.fieldIndex > 0;
+    const plannedTera = +(
-    return canTera && !plannedTera;
+      globalScene.currentBattle.preTurnCommands[0]?.command === Command.TERA && this.fieldIndex > 0
+    );
+    return canTera && currentTeras + plannedTera < MAX_TERAS_PER_ARENA;
   }
 
   toggleTeraButton() {

src/utils/pokemon-utils.ts

@@ -1,3 +1,4 @@
+import { MAX_TERAS_PER_ARENA } from "#app/constants";
 import { globalScene } from "#app/global-scene";
 import { POKERUS_STARTER_COUNT, speciesStarterCosts } from "#balance/starters";
 import { allSpecies } from "#data/data-lists";
@@ -136,7 +137,7 @@ export function getPokemonSpeciesForm(species: SpeciesId, formIndex: number): Po
  * Should really only be called with an enemy Pokémon, but will technically work with any Pokémon.
  *
  * @privateRemarks
- * Assumes that Pokémon with no trainer ever tera, so this must be changed if
+ * Assumes that Pokémon without a trainer will never tera, so this must be changed if
  * a wild Pokémon is allowed to tera, e.g. for a Mystery Encounter.
  */
 export function willTerastallize(pokemon: Pokemon): boolean {
@@ -150,13 +151,22 @@ export function willTerastallize(pokemon: Pokemon): boolean {
 }
 
 /**
- * Determine whether a player Pokémon can Terastallize
+ * Determine whether the Pokémon's species is tera capable, and that the player has acquired the tera orb.
+ * @param pokemon - The Pokémon to check
+ * @returns Whether
+ */
+export function canSpeciesTera(pokemon: Pokemon): boolean {
+  const hasTeraMod = globalScene.findModifier(modifier => modifier.is("TerastallizeAccessModifier")) != null;
+  const isBlockedForm = pokemon.isMega() || pokemon.isMax() || pokemon.hasSpecies(SpeciesId.NECROZMA, "ultra");
+  return hasTeraMod && !isBlockedForm;
+}
+
+/**
+ * Same as {@linkcode canSpeciesTera}, but also checks that the player has not already used their tera in the arena
  * @param pokemon - The Pokémon to check
  * @returns Whether the Pokémon can Terastallize
  */
 export function canTerastallize(pokemon: PlayerPokemon): boolean {
-  const hasTeraMod = globalScene.findModifier(modifier => modifier.is("TerastallizeAccessModifier")) != null;
+  const hasAvailableTeras = globalScene.arena.playerTerasUsed < MAX_TERAS_PER_ARENA;
-  const isBlockedForm = pokemon.isMega() || pokemon.isMax() || pokemon.hasSpecies(SpeciesId.NECROZMA, "ultra");
+  return hasAvailableTeras && canSpeciesTera(pokemon);
-  const currentTeras = globalScene.arena.playerTerasUsed === 0;
-  return hasTeraMod && !isBlockedForm && currentTeras;
 }